Murine T cell hybridomas for ovalbumin (OVA) and insulin have been produced and tested for ability to regulate the responses of specific B cells. Several categories of T cell hybridomas have been described. Some kinds of T cell hybridomas secrete IL-2 specifically when stimulated with the correct antigen, insulin or OVA, and in addition, help OVA-specific histocompatible B cells or TNP-specific histocompatible B cells make antibodies while others do not help specific B cells make antibodies. Other T cell hybridomas are self reactive but not antigen specific and these augment suboptimal numbers of antigen primed T cells in B cell secretion assays. For the insulin system, B cell hybridoma antibodies have been used to prepare anti-idiotypic reagents that do not affect IL-2 secretion by any anti-insulin-specific T cell hybridomas studies to-date. One of these anti-idiotypes clearly does produce regulatory effects in an insulin immune response when examined in in vivo or in vitro assays. Future work will involve further experiments to define cellular control of the network activated by this anti-idiotype. In other recently initiated experiments, human-mouse T cell hybrids are being used to study new human surface molecules at both the protein and gene levels.